The Government is to begin a consultation on raising the speed limit on Britain's motorways from 70mph to 80mph, it has been announced.

Transport Secretary Philip Hammond said the current limit was "out of date" and a higher one would bring economic benefits.

It is understood the consultation will be launched later this year with a view to introducing the new limit in 2013.

Mr Hammond said: "Now it is time to put Britain back in the fast lane of global economies and look again at the motorway speed limit which is nearly 50 years old, and out of date thanks to huge advances in safety and motoring technology.

"Increasing the motorway speed limit to 80mph would generate economic benefits of hundreds of millions of pounds through shorter journey times. So we will consult later this year on raising the limit to get Britain moving."

Professor Stephen Glaister, director of the RAC Foundation, said: "There are good reasons for making 80 the new 70, and good reasons not to. Drivers travelling that 10mph quicker might reach their destination sooner, but will use about 20% more fuel and emit 20% more CO2.

"There is also likely to be a slight increase in road casualties. And what about enforcement? If police follow existing guidelines, many people could do 90mph before action is taken."

He went on: "Before you change a speed limit, you have to know whether you are doing it for safety, economic or environmental reasons. Unfortunately not all of these are compatible."

Stephen Joseph, chief executive of Campaign for Better Transport, said: "Increasing the motorway speed limit to 80mph would not help the economy and would increase costs for drivers.

"It would also add to pollution and increase road casualties. Responsible motorists know that driving steadily at or below 70mph is most fuel-efficient, reduces jams and is safer."